1.7.3 for savoy.
1.8 for foix.
1.9.2 for Ryukyu.
As to strat preparation and feeling comfy: I just spent a lot of time comprending all game mechanics in my first months of playing. ALL game mechanics, even the hard/shady ones like PU mechanic. I then combined that with strategical insight (Risk board game experience?
), taking full benefit of opportunistic chances. Planning ahead is needed for a WC. Also, focussing on MORE then one thing at once is important. Most folks fight one war, and focus only on that. Finally, fighting in different continents at once to spread AE gain there over all the religions in all those continents is important.
Example: I said many times in 1.7 that changing capital as any european western nation to the black sea region is insanely powerful. Conquer Georgia/Trebizond or any nation at south black sea with no cb war, release them as vassal. You can now core provinces that neighbour that vassal, on european region. Make that province your capital, and make a corridor from that capital, trough your vassal, into Asia towards Africa, India etc. You can core everything there as overseas now, while keeping a corridor. Note that In savoy run this overseas didn't work yet, but the strategy was the same. Fight on different continents. Blobbing is easier if you start from Black sea. Look at ottomans, enough said. And the religions? Orthodox nations won't care if you attack/core heathens.
Read the savoy run (link in signature) and you'll see what I mean. I made a VERY atypical Savoy before 1500 there.
As for this Ryukyu run: I made a rough plan before starting, and tried to execute it. The capital switching was planned ahead, although I was aiming at doing it through the red sea into Mediterenean. Looking back, that would have been better. I should have kept capital in Africa. But a capital In FRANCE proved to be irrestible, from AAR point of view.